two populations. 3 Growth rates were back calcu- 

 lated from these quartic equations. 



CALCULATED GROWTH 



Fork lengths attained at each year of life and 

 the annual increments were calculated by sex for 

 330 pygmy whitefish from Brooks Lake (table 5) 

 and 779 from South Bay (table 6). A comparison 

 of these growth rates reveals that pygmy whitefish 

 grew considerably faster in South Bay than in 

 Brooks Lake. The largest pygmy whitefish col- 

 lected from Brooks Lake was an 84-mm. mature 

 female that had just completed its third growing 

 season. Two slightly older (III+) but smaller, 

 slower growing females were collected from 

 Brooks Lake, In South Bay the largest and oldest 

 pygmy whitefish was a 163-mm. age V mature 

 female. 



During their first year of life, males in Brooks 

 Lake grew slightly faster than females. In sub- 

 sequent years in Brooks Lake and in all years in 

 Naknek Lake, females consistently grew T at a faster 

 rate than males (tables 5 and 6). Males in Lake 

 Superior grew slightly faster than females dur- 

 ing the first year, grew at about the same rate as 

 females during the second year, and grew slower 

 than females during later years. Male pygmy 

 whitefish in Lake McDonald, Mont., grew faster 

 in their first year but slower than females in sub- 

 sequent years, while females in Bull Lake, Mont., 

 grew faster in all years (Eschmeyer and Bailey, 

 1955). With minor variations, these growth pat- 

 terns are similar to those reported by McCart 

 (1963) for pygmy whitefish in MacLure, McLeese, 

 Cluculz, and Tacheeda Lakes, British Columbia. 

 Males grew at about the same rate as females for 

 the first 2 years, after which females consistently 

 grew faster than males. 



Table 5. — Average fork length at time of capture and 

 calculated length at end of each year of life for pygmy 

 whitefish collected in Brooks Lake during summer and fall 

 1962 



3 Additional study is needed to understand fully the curvi- 

 linear body-scale relation of these whitefish. Few specimens 

 have been collected from South Bay as small as the age I and II 

 fish from Brooks Lake with usable scales. Obviously the cal- 

 culated curve for South Bay fish below 75 mm. is not biologically 

 valid. With adequate data the lower portion of the South Bay 

 curve could approach the Brooks Lake curve for the same size 

 fish, in which ease a single equation might express the body- 

 scale relation for both populations. The problem is aggravated 

 by the ease with which small pygmy whitefish lose their rela- 

 tively large scales. Also, South Bay fish grow as large in 1 year 

 as Brooks Lake fish do in 2 years, and it is not known what ef- 

 fect different growth rates between populations or between year 

 classes within the same population have on body-scale relation 

 curvilinearity. 



Table 6. — Average fork length at time of capture and cal- 

 culated length at end of each year of life for pygmy 

 whitefish collected in South Bay during summer and 

 fall 1962 



The annual growth of female pygmy whitefish 

 from Lake Superior (Keweenaw and Siskiwit 

 Bays) , Mich., and Bull Lake and Lake McDonald, 

 Mont., when compared with growth of females 

 from Brooks Lake and South Bay (fig. 6), 

 revealed that the slow growth in Brooks Lake was 

 similar to that in Lake Superior, while growth 

 in South Bay was intermediate between growth 

 in Bull Lake and Lake McDonald. Comparisons 

 of annual growth rates of female pygmy whitefish 

 from the Naknek system with those from Mac- 

 Lure, McLeese, Cluculz, and Tacheeda Lakes (Mc- 

 Cart, 1963) indicate (fig. 6) that growth in South 

 Bay was intermediate between growth in Mc- 

 Leese and Cluculz Lakes, while growth in Brooks 

 Lake was slower than in any of the British Colum- 

 bia lakes. The length attained by pygmy white- 



PYGMY WHITEFISH OF SOUTHWEST ALASKA 



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